Laminated electrical contact assembly



A. LATOUR LAMINATED I ELECTRICAL CONTACT ASSEMBLY May 18, 1965 Filed Oct. 9, 1961 United States Patent 3,184,573 LAMINATED ELECTRICAL CGNTACT ASSEMBLY Andr Latour, Grenoble, France, assignor to Etablissements Merlin & Ger-in, Grenoble, France Filed Oct. 9, 1961, Ser. No. 143,861 Claims priority, application France, Oct. 13, 1969, 4,293, Patent 1,276,844 6 Claims. (Cl. wit-166) This invention relates generally to electrical contact assemblies and more specially to sliding contact assemblies for disconnecting switches of high current carrying capacities and for main contacts of circuit-breakers.

In apparatus comprising a blade member which on closing engages into a plurality of jaws, it is necessary to provide very powerful means of moving the blade member. These means must be capable of surmounting the antago nistic electrodynamic eitect caused by the current-loop formed at the instant when the blade member enters into contact with the jaws. As a result the control devices are bulky and increase greatly the cost price of the switches.

It is an object of the present invention to improve the conditions under which the disconnecting switches of the type mentioned are closed.

It is another object of the invention to decrease the weight and the dimensions of the control mechanism and, consequently, of the whole apparatus.

These and other objects and advantages will be apparent from the following specification, taken in conjunction with the accompanying drawing, of some embodiments of the invention given merely for the purpose of illustration.

In the drawing:

FIG. 1 shows diagrammatically a side elevation and a plan view of a contact assembly of the known type.

FIG. 2 illustrates in side elevation an assembly according to one embodiment of the invention.

FIG. 3 is a side elevation according to a second embodiment of the invention.

FIG. 4 is a side elevation of a third embodiment of the invention.

FIG. 5 shows, in side elevation and in plan, a fourth embodiment according to the invention.

In FIG. 1, the fixed contact 11 carries a plurality of parallel generally elongated contacts or jaws 12 in tiered or superimposed arrangement, each contact or pair of jaws comprising a pair of separable sides into and between which the blade contact 13 engages. The arrows 14 represent diagrammatically the current paths and it is seen that the points of change of direction 15 of the arrows are located in the immediate neighborhood of the contact zones so that the electrodynamic repulsive forces which are exerted between the current paths in the blade contact, on the one hand, and those in the jaws, on the other hand, are very great by reason of the small distance a which separates them.

FIG. 2 shows a blade contact which is slitted by means of a plurality of saw-cuts 16 which extend parallel to the jaws 12. As a result, the points of change of direction of the current paths are moved towards the rear edge of the blade 13. Thus the current paths which penetrate the blade contact 13 retain over a certain length their initial direction, so that the distance b between the current paths along the rear edge of the blade and those of the jaws is considerably increased and the electrodynamic repulsion greatly reduced.

For very high currents, it will be advantageous to have saw-cuts of graduated length, as shown in FIG. 3. This arrangement avoids a concentration of the current towards the rear of the blade, a concentration which could result in an inadmissible heating of this part of the blade.

If, for special reasons for example to provide greater mechanical strength, it is desired to avoid saw-cuts in the 3,l84,573 Patented May 18, 1%65 blade member, the improvement of the invention can be obtained by means of a contact member 17 set into the edge of the movable blade facing the contact jaws and which alone engages into the jaws. As shown in FIG. 4-, here again the current paths conserve in the movable member their initial direction over a certain length so that the points of change of direction are removed from the contact zone, so that the electrodynamic repulsion is reduced.

FIG. 5 shows a modification of the embodiment of FIG. 4. The blade member is composed of two blades 18 and 19 between which is riveted or bolted the contact member 20 whose rear edge 21 is thicker. Insulating spacers 24 are provided between the blades 18 and 19. As the contact member 20 is in electrical contact with blades 18 and i9 only along the surfaces 22 and 23, the points of change or direction of the current paths are displaced towards the rear edge of the blade member.

It is known that in power circuit-breakers, the interrupting device comprises main contacts and sparking contacts. The main contacts which, in principle, should open without sparking may be considered to some extent as the contacts of a disconnecting switch. Thus the main movable contact is usually carried or formed by a disconnecting blade member.

In practice, it is seen that in spite of the presence of sparking contacts, the main contacts interrupt a current which, sometimes, leaves traces on the contact. In providing saw-cuts on the blade member, these burning traces on the main contacts are considerably reduced so that not only the conditions of closing but also those of opening can be considerably improved.

What is claimed is:

1. An electrical contact assembly comprising a movable contact and a fixed contact,

a plurality of separate contact elements mounted in spaced substantially parallel relation on said fixed contact and constituting parallel paths for the electrical current in the closed position of the contacts,

said contact elements consisting each of two elongated resilient jaws,

said movable contact consists of a movable blade disposed for engagement between said two elongated jaws of each of said contact elements in the closed position of the contacts,

said movable blade having a plurality of parallel spaced slits disposed relative to said contact elements to pro vide at least one slit extending in parallel relationship between two successive contact elements.

2. An electrical contact assembly comprising a movable contact, a

a plurality of separate contact elements mounted in spaced substantially parallel relation on said fixed contact and constituting parallel paths for the electrical current in the closed position of the contacts,

said contact elements consisting each of two elongated aws,

means for pressing said jaws toward each other,

said movable contact consisting of a movable blade disposed for engagement between said two elongated jaws of each of said contact elements in the closed position of the contacts,

said movable blade having a plurality of parallel spaced slits disposed relative to said contact elements to provide at least one slit extending in parallel relationship between two successive contact elements.

3. An electrical contact assembly comprising a movable contact and a fixed contact,

a plurality of separate contact elements mounted in spaced substantially parallel relation on said fixed contact and constituting parallel paths for the electrical ctu'rent in the closed position of the contacts,

said contact elements consisting each of two elongated jaws being prestressed toward each other,

said movable contact consisting of a movable blade disposed for engagement between said two elongated jaws of each of said contact elements in the closed position of the contacts,

said movable blade having a plurality of parallel spaced slits disposed relative to said contact elements to provide at least one slit extending in parallel relationship between two successive contact elements.

4. An electrical contact assembly according to claim 1,

wherein said slits have the form of saw-cuts of graduated and a movable contact,

said fixed contact including a plurality of spring contact elements defining parallel paths for the current in the closed position of the contacts,

each spring contact element comprising a pair of resiliently separable jaws,

a pair of parallel, elongated switch blades mounted on said movable contact and forming a unitary structure movable relative to said spring contact elements,

said switch blades extending perpendicularly to said parallel paths in the closed position of said contacts,

blades and a contact zone with said spring contact elements, j said two contact zones being spaced relatively far apart. 6. An electrical contact assembly as set forth in claim 1 wherein said contact elements define a contact zone on said blade contact in the closed position, said slits extending beyond said contact zone.

References Cited by the Examiner UNITED STATES PATENTS 1,546,272 7/25 Wede'man 200-166 1,769,279 7/30 True 200-166 2,120,396 6/38 Domaleski 200-166 2,765,380 10/56 Graybill 200-170 BERNARD A. GILHEANY, Primary Examiner.

ROBERT K. SCI-IAEFER, Examiner. 

1. AN ELECTRICAL CONTACT ASSEMBLY COMPRISING A MOVABLE CONTACT AND A FIXED CONTACT, A PLURALITY OF SEPARATE CONTACT ELEMENTS MOUNTED IN SPACED SUBSTANTIALLY PARALLEL RELATION ON SAID FIXED CONTACT AND CONSTITUTING PARALLEL PATHS FOR THE ELECTRICAL CURRENT IN THE CLOSED POSITION OF THE CONTACTS, SAID CONTACT ELEMENTS CONSISTING EACH OF TWO ELONGATED RESILIENT JAWS, SAID MOVABLE CONTACT CONSISTS OF A MOVABLE BLADE DISPOSED FOR ENGAGEMENT BETWEEN SAID TWO ELONGATED JAWS OF EACH OF SAID CONTACT ELEMENTS IN THE CLOSED POSITION OF THE CONTACTS, SAID MOVABLE BLADE HAVING A PLURALITY OF PARALLEL SPACED SLITS DISPOSED RELATIVE TO SAID CONTACT ELEMENTS TO PROVIDE AT LEAST ONE SLIT EXTENDING IN PARALLEL RELATIONSHIP BETWEEN TWO SUCCESSIVE CONTACT ELEMENTS. 